1. Field of the Invention
The invention relates to a method for the metallic joining of profiled rails in the longitudinal direction, e.g., railroad rails, beams or the like, by friction welding, in which, in a first step a heating of the rail ends to a joining temperature takes place by pressing together the faces while simultaneously moving them relative to one another and in a second step a joining of the rails takes place after alignment of the contours or the cross sections by pressing the faces together.
2. Discussion of Background Information
A metallic joining of the faces of rods can be advantageously accomplished by friction welding, whereby heating the faces pressed against one another or applying heat to the rod ends can be achieved by a relative movement of the same with respect to one another.
The relative movement can be achieved as a rotary motion of at least one rod at a rotational speed and/or with a direction of rotation about the common axis differing from the rod opposite, or at least one of the rod ends is moved to and from and/or in a circling or orbital manner perpendicular to the axis aligned in a different manner compared to the opposite one.
In particular for long rods with a respectively high mass, it is advantageous for heating the rod ends to be joined to move them cyclically relative to one another essentially perpendicular to the axis, i.e., not rotating.
A friction welding method and a device for the friction welding of pipes is known from U.S. Pat. No. 5,697,545. According to this document, the faces of two pipe parts are placed against one another with the application of pressure and a relative oscillatory movement of the faces takes place to heat the joint area by a magnetostrictive transducer.
A method and a vibratory welding head for friction welding joining or deburring technical components with any contour of the surfaces to be welded has become known from European Patent Application No. EP 0 707 919 A1. According to the proposal, the friction welding head is equipped with a control eccentric and a parallel guide through which a rotational energy on the input side can be converted into a circular energy of motion guided in a parallel manner. According to the method, for the heating process a component is moved slightly by a vibratory welding head about the center of the fixed component in a friction connection.
A friction welding method is disclosed in GB 1 293 531 according to which in the heating step the faces of the rod ends placed against one another are moved in a relative orbital manner. This relative orbital movement can be circular, elliptical or in a different manner in a form of a Lissajous figure.
A method of friction welding railroad rails and similar beam profiles is known from German Patent Application No. DE 198 07 457 A1. According to the application, it is proposed to move an intermediate piece in linear or orbital oscillation between the rail ends to be joined, while parallel thereto the two fixed rail ends are pressed toward one another in the rail longitudinal direction against the intermediate piece in order to generate through friction energy the heat necessary for welding on both contact surfaces between respectively one rail end and respectively one sectional area of the intermediate piece. However, this type of joining of rails exhibits two friction welding joint surfaces due to the method.
For rails with great longitudinal extension, Austrian Patent No. AT 411 883 B discloses a method for the metallic joining of the face or cross-sectional surfaces by friction welding. After the ends are dressed perpendicular to the axes, it is provided for a heating step that the dressed cross-sectional areas are placed against one another, acted upon with pressure and the two rail ends are moved in an oscillating manner in an opposite direction relative to each other.
For a face connection of, where necessary, profiled rods by friction welding, according to the technical art for heating the face ends a relative movement by rotation about the rod axis is not exclusively necessary, relative movements of the pressurized cross-sectional areas, which are oscillating, where necessary orbitally oscillating, can also be used.
However, a metallic joining of rails and beams by friction welding with oscillating relative movements of the pressurized faces during heating can cause great forces for a movement of the rail ends and in particular a consequent displacement of the flange ends, that is a local discontinuity of the rail cross section, in the longitudinal direction at the weld point.